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- /* Native-dependent code for GNU/Linux x86-64.
- Copyright (C) 2001-2022 Free Software Foundation, Inc.
- Contributed by Jiri Smid, SuSE Labs.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #include "defs.h"
- #include "inferior.h"
- #include "regcache.h"
- #include "elf/common.h"
- #include <sys/uio.h>
- #include "nat/gdb_ptrace.h"
- #include <asm/prctl.h>
- #include <sys/reg.h>
- #include "gregset.h"
- #include "gdb_proc_service.h"
- #include "amd64-nat.h"
- #include "amd64-tdep.h"
- #include "amd64-linux-tdep.h"
- #include "i386-linux-tdep.h"
- #include "gdbsupport/x86-xstate.h"
- #include "x86-linux-nat.h"
- #include "nat/linux-ptrace.h"
- #include "nat/amd64-linux-siginfo.h"
- /* This definition comes from prctl.h. Kernels older than 2.5.64
- do not have it. */
- #ifndef PTRACE_ARCH_PRCTL
- #define PTRACE_ARCH_PRCTL 30
- #endif
- struct amd64_linux_nat_target final : public x86_linux_nat_target
- {
- /* Add our register access methods. */
- void fetch_registers (struct regcache *, int) override;
- void store_registers (struct regcache *, int) override;
- bool low_siginfo_fixup (siginfo_t *ptrace, gdb_byte *inf, int direction)
- override;
- };
- static amd64_linux_nat_target the_amd64_linux_nat_target;
- /* Mapping between the general-purpose registers in GNU/Linux x86-64
- `struct user' format and GDB's register cache layout for GNU/Linux
- i386.
- Note that most GNU/Linux x86-64 registers are 64-bit, while the
- GNU/Linux i386 registers are all 32-bit, but since we're
- little-endian we get away with that. */
- /* From <sys/reg.h> on GNU/Linux i386. */
- static int amd64_linux_gregset32_reg_offset[] =
- {
- RAX * 8, RCX * 8, /* %eax, %ecx */
- RDX * 8, RBX * 8, /* %edx, %ebx */
- RSP * 8, RBP * 8, /* %esp, %ebp */
- RSI * 8, RDI * 8, /* %esi, %edi */
- RIP * 8, EFLAGS * 8, /* %eip, %eflags */
- CS * 8, SS * 8, /* %cs, %ss */
- DS * 8, ES * 8, /* %ds, %es */
- FS * 8, GS * 8, /* %fs, %gs */
- -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, /* MPX registers BND0 ... BND3. */
- -1, -1, /* MPX registers BNDCFGU, BNDSTATUS. */
- -1, -1, -1, -1, -1, -1, -1, -1, /* k0 ... k7 (AVX512) */
- -1, -1, -1, -1, -1, -1, -1, -1, /* zmm0 ... zmm7 (AVX512) */
- -1, /* PKEYS register PKRU */
- ORIG_RAX * 8 /* "orig_eax" */
- };
- /* Transfering the general-purpose registers between GDB, inferiors
- and core files. */
- /* See amd64_collect_native_gregset. This linux specific version handles
- issues with negative EAX values not being restored correctly upon syscall
- return when debugging 32-bit targets. It has no effect on 64-bit
- targets. */
- static void
- amd64_linux_collect_native_gregset (const struct regcache *regcache,
- void *gregs, int regnum)
- {
- amd64_collect_native_gregset (regcache, gregs, regnum);
- struct gdbarch *gdbarch = regcache->arch ();
- if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
- {
- /* Sign extend EAX value to avoid potential syscall restart
- problems.
- On Linux, when a syscall is interrupted by a signal, the
- (kernel function implementing the) syscall may return
- -ERESTARTSYS when a signal occurs. Doing so indicates that
- the syscall is restartable. Then, depending on settings
- associated with the signal handler, and after the signal
- handler is called, the kernel can then either return -EINTR
- or it can cause the syscall to be restarted. We are
- concerned with the latter case here.
-
- On (32-bit) i386, the status (-ERESTARTSYS) is placed in the
- EAX register. When debugging a 32-bit process from a 64-bit
- (amd64) GDB, the debugger fetches 64-bit registers even
- though the process being debugged is only 32-bit. The
- register cache is only 32 bits wide though; GDB discards the
- high 32 bits when placing 64-bit values in the 32-bit
- regcache. Normally, this is not a problem since the 32-bit
- process should only care about the lower 32-bit portions of
- these registers. That said, it can happen that the 64-bit
- value being restored will be different from the 64-bit value
- that was originally retrieved from the kernel. The one place
- (that we know of) where it does matter is in the kernel's
- syscall restart code. The kernel's code for restarting a
- syscall after a signal expects to see a negative value
- (specifically -ERESTARTSYS) in the 64-bit RAX register in
- order to correctly cause a syscall to be restarted.
-
- The call to amd64_collect_native_gregset, above, is setting
- the high 32 bits of RAX (and other registers too) to 0. For
- syscall restart, we need to sign extend EAX so that RAX will
- appear as a negative value when EAX is set to -ERESTARTSYS.
- This in turn will cause the signal handling code in the
- kernel to recognize -ERESTARTSYS which will in turn cause the
- syscall to be restarted.
- The test case gdb.base/interrupt.exp tests for this problem.
- Without this sign extension code in place, it'll show
- a number of failures when testing against unix/-m32. */
- if (regnum == -1 || regnum == I386_EAX_REGNUM)
- {
- void *ptr = ((gdb_byte *) gregs
- + amd64_linux_gregset32_reg_offset[I386_EAX_REGNUM]);
- *(int64_t *) ptr = *(int32_t *) ptr;
- }
- }
- }
- /* Fill GDB's register cache with the general-purpose register values
- in *GREGSETP. */
- void
- supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
- {
- amd64_supply_native_gregset (regcache, gregsetp, -1);
- }
- /* Fill register REGNUM (if it is a general-purpose register) in
- *GREGSETP with the value in GDB's register cache. If REGNUM is -1,
- do this for all registers. */
- void
- fill_gregset (const struct regcache *regcache,
- elf_gregset_t *gregsetp, int regnum)
- {
- amd64_linux_collect_native_gregset (regcache, gregsetp, regnum);
- }
- /* Transfering floating-point registers between GDB, inferiors and cores. */
- /* Fill GDB's register cache with the floating-point and SSE register
- values in *FPREGSETP. */
- void
- supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
- {
- amd64_supply_fxsave (regcache, -1, fpregsetp);
- }
- /* Fill register REGNUM (if it is a floating-point or SSE register) in
- *FPREGSETP with the value in GDB's register cache. If REGNUM is
- -1, do this for all registers. */
- void
- fill_fpregset (const struct regcache *regcache,
- elf_fpregset_t *fpregsetp, int regnum)
- {
- amd64_collect_fxsave (regcache, regnum, fpregsetp);
- }
- /* Transferring arbitrary registers between GDB and inferior. */
- /* Fetch register REGNUM from the child process. If REGNUM is -1, do
- this for all registers (including the floating point and SSE
- registers). */
- void
- amd64_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum)
- {
- struct gdbarch *gdbarch = regcache->arch ();
- int tid;
- /* GNU/Linux LWP ID's are process ID's. */
- tid = regcache->ptid ().lwp ();
- if (tid == 0)
- tid = regcache->ptid ().pid (); /* Not a threaded program. */
- if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum))
- {
- elf_gregset_t regs;
- if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0)
- perror_with_name (_("Couldn't get registers"));
- amd64_supply_native_gregset (regcache, ®s, -1);
- if (regnum != -1)
- return;
- }
- if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum))
- {
- elf_fpregset_t fpregs;
- if (have_ptrace_getregset == TRIBOOL_TRUE)
- {
- char xstateregs[X86_XSTATE_MAX_SIZE];
- struct iovec iov;
- /* Pre-4.14 kernels have a bug (fixed by commit 0852b374173b
- "x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on
- Intel Skylake CPUs") that sometimes causes the mxcsr location in
- xstateregs not to be copied by PTRACE_GETREGSET. Make sure that
- the location is at least initialized with a defined value. */
- memset (xstateregs, 0, sizeof (xstateregs));
- iov.iov_base = xstateregs;
- iov.iov_len = sizeof (xstateregs);
- if (ptrace (PTRACE_GETREGSET, tid,
- (unsigned int) NT_X86_XSTATE, (long) &iov) < 0)
- perror_with_name (_("Couldn't get extended state status"));
- amd64_supply_xsave (regcache, -1, xstateregs);
- }
- else
- {
- if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
- perror_with_name (_("Couldn't get floating point status"));
- amd64_supply_fxsave (regcache, -1, &fpregs);
- }
- }
- }
- /* Store register REGNUM back into the child process. If REGNUM is
- -1, do this for all registers (including the floating-point and SSE
- registers). */
- void
- amd64_linux_nat_target::store_registers (struct regcache *regcache, int regnum)
- {
- struct gdbarch *gdbarch = regcache->arch ();
- int tid;
- /* GNU/Linux LWP ID's are process ID's. */
- tid = regcache->ptid ().lwp ();
- if (tid == 0)
- tid = regcache->ptid ().pid (); /* Not a threaded program. */
- if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum))
- {
- elf_gregset_t regs;
- if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0)
- perror_with_name (_("Couldn't get registers"));
- amd64_linux_collect_native_gregset (regcache, ®s, regnum);
- if (ptrace (PTRACE_SETREGS, tid, 0, (long) ®s) < 0)
- perror_with_name (_("Couldn't write registers"));
- if (regnum != -1)
- return;
- }
- if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum))
- {
- elf_fpregset_t fpregs;
- if (have_ptrace_getregset == TRIBOOL_TRUE)
- {
- char xstateregs[X86_XSTATE_MAX_SIZE];
- struct iovec iov;
- iov.iov_base = xstateregs;
- iov.iov_len = sizeof (xstateregs);
- if (ptrace (PTRACE_GETREGSET, tid,
- (unsigned int) NT_X86_XSTATE, (long) &iov) < 0)
- perror_with_name (_("Couldn't get extended state status"));
- amd64_collect_xsave (regcache, regnum, xstateregs, 0);
- if (ptrace (PTRACE_SETREGSET, tid,
- (unsigned int) NT_X86_XSTATE, (long) &iov) < 0)
- perror_with_name (_("Couldn't write extended state status"));
- }
- else
- {
- if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
- perror_with_name (_("Couldn't get floating point status"));
- amd64_collect_fxsave (regcache, regnum, &fpregs);
- if (ptrace (PTRACE_SETFPREGS, tid, 0, (long) &fpregs) < 0)
- perror_with_name (_("Couldn't write floating point status"));
- }
- }
- }
- /* This function is called by libthread_db as part of its handling of
- a request for a thread's local storage address. */
- ps_err_e
- ps_get_thread_area (struct ps_prochandle *ph,
- lwpid_t lwpid, int idx, void **base)
- {
- if (gdbarch_bfd_arch_info (ph->thread->inf->gdbarch)->bits_per_word == 32)
- {
- unsigned int base_addr;
- ps_err_e result;
- result = x86_linux_get_thread_area (lwpid, (void *) (long) idx,
- &base_addr);
- if (result == PS_OK)
- {
- /* Extend the value to 64 bits. Here it's assumed that
- a "long" and a "void *" are the same. */
- (*base) = (void *) (long) base_addr;
- }
- return result;
- }
- else
- {
- /* FIXME: ezannoni-2003-07-09 see comment above about include
- file order. We could be getting bogus values for these two. */
- gdb_assert (FS < ELF_NGREG);
- gdb_assert (GS < ELF_NGREG);
- switch (idx)
- {
- case FS:
- {
- unsigned long fs;
- errno = 0;
- fs = ptrace (PTRACE_PEEKUSER, lwpid,
- offsetof (struct user_regs_struct, fs_base), 0);
- if (errno == 0)
- {
- *base = (void *) fs;
- return PS_OK;
- }
- }
- break;
- case GS:
- {
- unsigned long gs;
- errno = 0;
- gs = ptrace (PTRACE_PEEKUSER, lwpid,
- offsetof (struct user_regs_struct, gs_base), 0);
- if (errno == 0)
- {
- *base = (void *) gs;
- return PS_OK;
- }
- }
- break;
- default: /* Should not happen. */
- return PS_BADADDR;
- }
- }
- return PS_ERR; /* ptrace failed. */
- }
- /* Convert a ptrace/host siginfo object, into/from the siginfo in the
- layout of the inferiors' architecture. Returns true if any
- conversion was done; false otherwise. If DIRECTION is 1, then copy
- from INF to PTRACE. If DIRECTION is 0, copy from PTRACE to
- INF. */
- bool
- amd64_linux_nat_target::low_siginfo_fixup (siginfo_t *ptrace,
- gdb_byte *inf,
- int direction)
- {
- struct gdbarch *gdbarch = get_frame_arch (get_current_frame ());
- /* Is the inferior 32-bit? If so, then do fixup the siginfo
- object. */
- if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32)
- return amd64_linux_siginfo_fixup_common (ptrace, inf, direction,
- FIXUP_32);
- /* No fixup for native x32 GDB. */
- else if (gdbarch_addr_bit (gdbarch) == 32 && sizeof (void *) == 8)
- return amd64_linux_siginfo_fixup_common (ptrace, inf, direction,
- FIXUP_X32);
- else
- return false;
- }
- void _initialize_amd64_linux_nat ();
- void
- _initialize_amd64_linux_nat ()
- {
- amd64_native_gregset32_reg_offset = amd64_linux_gregset32_reg_offset;
- amd64_native_gregset32_num_regs = I386_LINUX_NUM_REGS;
- amd64_native_gregset64_reg_offset = amd64_linux_gregset_reg_offset;
- amd64_native_gregset64_num_regs = AMD64_LINUX_NUM_REGS;
- gdb_assert (ARRAY_SIZE (amd64_linux_gregset32_reg_offset)
- == amd64_native_gregset32_num_regs);
- linux_target = &the_amd64_linux_nat_target;
- /* Add the target. */
- add_inf_child_target (linux_target);
- }
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